Zapatero had vowed following his Socialist Party's election win last month to pull Spanish troops from Iraq unless they come under UN command by June 30 when their mandate expires.

"I have given the order to the defense minister to take the necessary measures so that Spanish troops are withdrawn from Iraq as soon as possible and with maximum security," Zapatero said in an address on Spanish television a day after formally taking office.

"It does not look like a UN resolution will match the content" of the Spanish demands for the continued presence of the troops, the prime minister said.

US President George W. Bush and British Prime Minister Tony Blair on Friday pledged to give the United Nations a central role in the transfer of power to the Iraqi interim government, planned for June 30.

The move had been seen as a way to keep countries like Spain on board with the US-led coalition, despite a recent surge in violence and hostage-taking in Iraq.

Zapatero gave no details on the timetable for the withdrawal, but government sources said the pullout could take place over about 50 days.

A foreign ministry official in Cairo said Spain's Foreign Minister Miguel Angel Moratinos had informed Egyptian counterpart Ahmed Maher that Madrid plans to pull its troops out of Iraq "within 15 days", but Maher later said that no specific timeframe was mentioned.

The White House said the United States would continue its close cooperation with Spain in the war against terrorism despite the decision.

"We will work with our coalition partners in Iraq and the Spanish government and expect they will implement their decision in a coordinated, responsible and orderly manner," White House spokesman Ken Lisaius said.

A US State Department official said the Spanish decision was not unexpected in Washington.

"This is not unexpected. We recognized they were going to do this," the official said on condition of anonymity.

Madrid's 1,300 soldiers are part of a 9,000-strong Polish-led force controlling a swathe of Iraq south of Baghdad, and constitute the sixth-largest national contingent in the coalition force.

In Warsaw, Poland's Defense Minister Jerzy Szmajdzinski expressed surprise at the Spanish move.

"We were expecting such a decision will be taken when a renewal of the contingent" takes place in a few days, he told public television.

But he said Poland would not be sending additional troops to replace the Spanish soldiers.

Zapatero said Sunday the decision to withdraw Spanish troops "also responds to the aim of contributing to the fight that the international community is waging against terrorism while closely respecting international law".

He promised, however, that Spain would take part in "collaboration projects" in Iraq.

Government sources said Madrid had informed about a dozen allied countries and others taking part in the coalition of its decision at least two weeks ago.

Zapatero's conservative predecessor, Jose Maria Aznar, sent 1,300 troops to serve as part of the US-led coalition in Iraq in August 2003, in a move which led to huge popular protests across Spain.

Aznar's dogged pro-US stance over Iraq, coupled with his early insistence that Basque militants and not Islamic extremists carried out the March 11 Madrid train bombings which killed 191 people in Spain's worst terrorist attack, helped swing the March 14 election to the Socialists.

Following Zapatero's announcement, several hundred people, some waving banners reading "Peace", gathered in central Madrid late Sunday to celebrate.

The El Pais daily meanwhile reported Sunday that new Foreign Minister Miguel Angel Moratinos is to meet with his US counterpart Colin Powell in Washington on Wednesday to propose alternative ways to cooperate over Iraq if Spanish troops leave the country.

During his Washington visit, Moratinos will reiterate Spanish resolve to pull its soldiers from Iraq but will express the country's determination to continue contributing to the reconstruction of the country, El Pais said.

Part of that includes following through with the economic commitment made by Spain as well as continued humanitarian aid, it added.

Moratinos will also emphasize Spain's commitment to the fight against terrorism and it will to be one of Washington's closest allies in that fight.

The withdrawal of Spanish troops was also demanded by several leftist political parties, 19 of whose deputies backed Zapatero as prime minister in his election by the parliament on Friday.

WAR.WIRE